M306V2ME Datasheet, PDF (149/276 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M306V2ME-XXXFP
M306V2EEFP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
2.12 A-D Converter
The A-D converter consists of one 8-bit successive approximation A-D converter circuit with a capacitive coupling
amplifier. Pins P102 to P107 also function as the analog signal input pins. The direction registers of these pins for A-
D conversion must therefore be set to input. The Vref connect bit (bit 5 at address 03D716) can be used to isolate the
resistance ladder of the A-D converter from the reference voltage (VREF) when the A-D converter is not used. Doing
so stops any current flowing into the resistance ladder from VREF, reducing the power dissipation. When using the A-
D converter, start A-D conversion only after setting bit 5 of 03D716 to connect VREF.
The result of A-D conversion is stored in the A-D registers of the selected pins.
Table 2.12.1 shows the performance of the A-D converter. Figure 2.12.1 shows the block diagram of the A-
D converter, and Figures 2.12.2 to 2.12.5 show the A-D converter-related registers.
Table 2.12.1 Performance of A-D converter
Item
Performance
Method of A-D conversion Successive approximation (capacitive coupling amplifier)
Analog input voltage (Note 1) 0V to AVCC (VCC)
Operating clock φAD (Note 2) fAD/divide-by-2 of fAD/divide-by-4 of fAD, fAD=f(XIN)
Resolution
8-bit
Absolute precision
VCC = 5V • Without sample and hold function: ±5 LSB
• With sample and hold function: ±5 LSB
Operating modes
One-shot mode, repeat mode, single sweep mode, repeat sweep mode 0,
and repeat sweep mode 1
Analog input pins
6 pins (AN0 to AN5)
A-D conversion start condition • Software trigger
A-D conversion starts when the A-D conversion start flag changes to “1”
Conversion speed per pin • Without sample and hold function
49 φAD cycles
• With sample and hold function
28 φAD cycles
Notes 1: Does not depend on use of sample and hold function.
2: Divide the frequency if f(XIN) exceeds 10 MHz, and make φAD frequency equal to 10 MHz. Without
sample and hold function, set the φAD frequency to 250kHz min.
With the sample and hold function, set the φAD frequency to 1MHz min.
Rev. 1.0
149